//
//  NSData+Compression.m
//  Project
//
//  Created by  CarlsonLee on 2018/12/7.
//  Copyright © 2018年 YANJING. All rights reserved.
//

#import "NSData+Compression.h"
#include <zlib.h>

@implementation NSData (Compression)

- (NSData *)gel_gzipInflate {
    if ([self length] == 0) return self;
    
    unsigned full_length = (unsigned)[self length];
    unsigned half_length = (unsigned)[self length] / 2;
    
    NSMutableData *decompressed = [NSMutableData
                                   dataWithLength:full_length + half_length];
    BOOL done = NO;
    int status;
    
    z_stream strm;
    strm.next_in = (Bytef *)[self bytes];
    strm.avail_in = (unsigned)[self length];
    strm.total_out = 0;
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    
    if (inflateInit2(&strm, (15 + 32)) != Z_OK) return nil;
    while (!done) {
        // Make sure we have enough room and reset the lengths.
        if (strm.total_out >= [decompressed length])
            [decompressed increaseLengthBy:half_length];
        strm.next_out = [decompressed mutableBytes] + strm.total_out;
        strm.avail_out = (uInt)([decompressed length] - strm.total_out);
        
        // Inflate another chunk.
        status = inflate(&strm, Z_SYNC_FLUSH);
        if (status == Z_STREAM_END) done = YES;
        else if (status != Z_OK) break;
    }
    if (inflateEnd(&strm) != Z_OK) return nil;
    
    // Set real length.
    if (done) {
        [decompressed setLength:strm.total_out];
        return [NSData dataWithData:decompressed];
    } else return nil;
}

- (NSData *)gel_gzipDeflate {
    if ([self length] == 0) return self;
    
    z_stream strm;
    
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.total_out = 0;
    strm.next_in = (Bytef *)[self bytes];
    strm.avail_in = (uInt)[self length];
    
    // Compresssion Levels:
    //   Z_NO_COMPRESSION
    //   Z_BEST_SPEED
    //   Z_BEST_COMPRESSION
    //   Z_DEFAULT_COMPRESSION
    
    if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (15 + 16),
                     8, Z_DEFAULT_STRATEGY) != Z_OK)
        return nil;
    
    // 16K chunks for expansion
    NSMutableData *compressed = [NSMutableData dataWithLength:16384];
    
    do {
        if (strm.total_out >= [compressed length])
            [compressed increaseLengthBy:16384];
        
        strm.next_out = [compressed mutableBytes] + strm.total_out;
        strm.avail_out = (uInt)([compressed length] - strm.total_out);
        
        deflate(&strm, Z_FINISH);
    }
    while (strm.avail_out == 0);
    
    deflateEnd(&strm);
    
    [compressed setLength:strm.total_out];
    return [NSData dataWithData:compressed];
}

- (NSData *)gel_zlibInflate {
    if ([self length] == 0) return self;
    
    NSUInteger full_length = [self length];
    NSUInteger half_length = [self length] / 2;
    
    NSMutableData *decompressed = [NSMutableData
                                   dataWithLength:full_length + half_length];
    BOOL done = NO;
    int status;
    
    z_stream strm;
    strm.next_in = (Bytef *)[self bytes];
    strm.avail_in = (uInt)full_length;
    strm.total_out = 0;
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    
    if (inflateInit(&strm) != Z_OK) return nil;
    
    while (!done) {
        // Make sure we have enough room and reset the lengths.
        if (strm.total_out >= [decompressed length])
            [decompressed increaseLengthBy:half_length];
        strm.next_out = [decompressed mutableBytes] + strm.total_out;
        strm.avail_out = (uInt)([decompressed length] - strm.total_out);
        
        // Inflate another chunk.
        status = inflate(&strm, Z_SYNC_FLUSH);
        if (status == Z_STREAM_END) done = YES;
        else if (status != Z_OK) break;
    }
    if (inflateEnd(&strm) != Z_OK) return nil;
    
    // Set real length.
    if (done) {
        [decompressed setLength:strm.total_out];
        return [NSData dataWithData:decompressed];
    } else return nil;
}

- (NSData *)gel_zlibDeflate {
    if ([self length] == 0) return self;
    
    z_stream strm;
    
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.total_out = 0;
    strm.next_in = (Bytef *)[self bytes];
    strm.avail_in = (uInt)[self length];
    
    // Compresssion Levels:
    //   Z_NO_COMPRESSION
    //   Z_BEST_SPEED
    //   Z_BEST_COMPRESSION
    //   Z_DEFAULT_COMPRESSION
    
    if (deflateInit(&strm, Z_DEFAULT_COMPRESSION) != Z_OK) return nil;
    
    // 16K chuncks for expansion
    NSMutableData *compressed = [NSMutableData dataWithLength:16384];
    
    do {
        if (strm.total_out >= [compressed length])
            [compressed increaseLengthBy:16384];
        
        strm.next_out = [compressed mutableBytes] + strm.total_out;
        strm.avail_out = (uInt)([compressed length] - strm.total_out);
        
        deflate(&strm, Z_FINISH);
    }
    while (strm.avail_out == 0);
    
    deflateEnd(&strm);
    
    [compressed setLength:strm.total_out];
    return [NSData dataWithData:compressed];
}


@end
